Power switch components for switching large currents are known in the related art. The declining power loss based on the flow of current through the power switch component was determined by the forward power losses of the semiconductor switch. In contrast, the most recent generations of power switch components such as, for example, trench MOSFETS, have forward power losses which may lie in the same range as the electrical losses of the contacting (for example, through bonding wires). This causes the contacting losses to be no longer negligible. From a thermal point of view, it is, however, more significant that the contacting and housing components that may possibly be used for current conduction no longer represent heat sinks but are instead heat sources. These heat sources may be a cause of interfering local temperature increases of the contacted semiconductor switch.
Another effect, which also results in an increased power loss in the area of the contacting zone, is transverse conduction losses within the metal plating layer of the semiconductor switch. In addition to the forward bias, in power switch components having structurally related inverse or body diodes there is also the possibility of a high heat input through the current-carrying contacting elements. In the automotive industry, battery polarity reversal is a typical example of non-homogeneous current distribution and accordingly heat distribution in negative polarity.
The above-mentioned effects may result in interfering local temperature increases of the semiconductor switch, which in turn limit the current-carrying capacity of the power switch component in at least some operating states. In practice, the result of these limitations is that larger switches are provided, which increases the cost of a system.
The corrective measures known in the related art typically start with the type of contacting, for example, using the so-called Cu clip or ribbon bond techniques. On the other hand, in integrated circuits (ICs), it is attempted to make better use of the thermal capacity of the semiconductor material. However, none of these techniques is capable of completely preventing local temperature increases.